1. Field of the Invention
The present invention relates to a communication apparatus connectable to a telephone apparatus, a method of controlling the same, and a storage medium.
2. Description of the Related Art
In recent years, next generation networks (NGN: Next Generation Network) that perform voice communication by IP (Internet Protocol) telephone, image communication by IP-FAX communication by the ITU-T recommendation T.38, or the like, are widely used. An NGN is an IP network, provided with a bandwidth guaranteeing function and a security function for the network itself, which realizes integrally a telephone service, a video communication service, a data communication service, or the like.
In addition, SIP (Session Initiation Protocol), with which, a virtual session between communication devices on an NGN is established, and a service is provided while the session is established, has spread and is utilized. A communication device that established a session by SIP, performs a call or image communication using a protocol such as IP, VOIP (Voice Over IP), or the like, or various forms of services are provided such as these being performed simultaneously.
Here, in the communication apparatus, various functions are provided, and there those by which, as a telephone function, for example, an IP telephone or a telephone apparatus corresponding to a PBX (Private Branch Exchange), a telephone apparatus is connectable as an external telephone. For controlling the telephone apparatus corresponding to the PBX, for example, an SLIC (Subscriber Line Interface Circuit) is used.
In a SLIC there is a function for performing D/A and A/D conversion of call voice signals, a function for performing generation of call signals for sounding an incoming call tone of the telephone apparatus, a function for detecting an off-hook of the telephone apparatus, and the like. In general, because it is desirable that the telephone apparatus is always in a usable state, it is necessary to be in an operable state with electric power constantly being supplied to a telephone control unit (the previously described SLIC).
On the other hand, in communication apparatuses in recent years, there are those for which a power saving mode is arranged. When the communication apparatus transitions into the power saving mode, scaling down the consumption of the electric power of the communication apparatus on the whole becomes possible by stopping the electric power supply to a portion of the constituent elements.
In Japanese Patent Laid-Open No. 2009-171287, a configuration in which, in a facsimile apparatus to which a telephone apparatus is connected, an off-hook detection is performed by electric power supplied from a sub electric power supply after a power saving mode is transitioned into is disclosed.
There is an image communication apparatus in which an IPFAX function is included which is an image communication apparatus to which a telephone apparatus is connectable as an external telephone. Control of the connected telephone apparatus is realized by a SLIC (a telephone control unit) having functions such as voice data conversion, call signal generation, off-hook detection, or the like. In order to put the telephone apparatus into a state in which it is continuously usable (a continuously off-hook detection capable state), it is necessary to continuously supply electric power to the SLIC. However, because the SLIC consumes large amounts of electric power, electric power consumption becomes large when electric power is continuously supplied to the SLIC.